This looks to have a central stem rather than growing shelf-like out of some wood. I don't think it is an immature Amauroderma rude as it appears to be rather thin at the margin. It could have been really useful to have an image of what it looked like underneath.
Its by the side of the dirt vehilcle track between hawker and the nature reserve. Ken I dont think it is Trametes now i have a better look. Unfortunately i didnt see the underside though,.